mwiener2

There is TONS more heat picked up by going through the hot fuel rails than from the pump.

evangt- the catted UP is strictly for cold start emissions and it was a bad idea. Subaru stopped using catted UP's in 2006. Blocking up these vents will NOT help cabin air quality. You are sealing up the vent, preventing fresh air from coming in. Imagine the blower on your car's HVAC system is like a hair dryer blowing through a paper towel tube. Now plug up one end of the tube. That's what you guys are doing by taping up those vents.

And not all of that wattage is converted into heat. The majority of it goes into pumping fuel.

No. You don't need it. But should you want it, that is the best and only option. If modulating the pump was important, there'd be more aftermarket fuel pump controllers.... and there are essentially none on the market right now.

Except that doesn't happen (evap) and all fuel pumps are rated for 100% duty cycle, all the time.

You've spent months trying to rewire the stock FPCM so you can run the pump at 30, 60, 100%. You could have spent an hour or two hardwiring the pump and been done with it at 100% flow all the time. Why do you want variable pump so bad? This is part of pay to play. It doesn't always mean money. In this case it means you give up variable pump control so you can move the fuel you need. I'll say this again. The FPCM is an engineered circuit. It was designed for a pump that draws less than 10amps. Unless you re-engineer the circuit, it will never be stout enough to do what you are trying to do.

So what's the big deal about having a fuel pump that can be ramped down?

I don't have a wideband and I'm probably a bit lean up top. But that's the joy of E85. Maybe try an Outback FPCM I dyno'd 436 awhp at 24psi boost. I was running 28-30psi a few months ago. Another shop owner up here has a 470 awhp 2.5rs that also has a walbro 255. I wouldn't suggest it to anyone, but it can do it. I have 3 aero pumps that would not hold proper fuel pressure in a car running 60psi base. Boost was 26, but one of the pumps dropped to 40psi at redline on a 7psi boost pull. This car has 10g wiring direct to the pump and would hold full voltage throughout a pull. All the pumps passed a flow test when removed from the car. Each pump performed properly for about a pull or two before failing. Aeromotive tech support claims cavitation on the impeller due to a negatively pressurized fuel tank. I say BS. A walbro 460 solved the problem. I had a Corvette with a 1000hp goal that had 2 aero's. First attempt the wiring supplied with the kit fried, killed one of the pumps. Put a new one in. Ran seperate 10g wire to each pump and fuel pressure would still drop off near redline when it was only making 600hp. Replaced with DW300's and amperage was down and fueling was up. I had similar experiences 3 years ago, let aeros sneak back in, but now they're out for good. Maybe think of the AEM320 as a middle ground pump.

That's another story altogether.... I've come across more bad ones than good ones. I refuse to sell them anymore. Under test conditions, they seem to work. In real world conditions, they don't, especially after some use. What measurable benefit are you getting by varying pump flow? Your modded motors will blow up long before you wear out the pump. The 0.02% gain in economy isn't it. The 5hp loss from hot fuel isn't it....

Have I ever said any of this wouldn't work? No. I just think you have a lot of misguided, unneeded modding to attain a laughable goal.

you can't even spell my name right when it's all over the place # 12,147 you gotta work to get numbers like this

If the Aero fixed the problem, you wouldn't be re-wiring your FPCM.

So no good replies? Maybe your aeromotive is faulty... it wouldn't be the first one.

So why does my Walbro 255 with stock wiring and FPCM get me to 450+ WHP on E85 (30% more fuel)?

There has to be heat to sink

Your not fixing it!

So what's the problem here? If the FPCM is not failing, then it is working properly and there is no issue. Why are you guys messing with them then? Bigger pumps require more current. If the system is not able to supply enough current, the voltage drops. You guys have recorded this. You put in larger wire that can handle more current and you noted a smaller drop in voltage. Something was still bottle-necking. It was the stock FPCM. You guys found that the STi module dropped less voltage and installed that, but still see a voltage drop. It's because the FPCM cannot handle the current you are trying to run through it. You can: 1) re-engineer the Subaru FPCM 2) Bypass the FPCM and hardwire the pump with a relay 3) Find an aftermarket pump controller #1 is a waste of time unless you can get Subaru to buy your new design #2 is the solution since cars #3 is the proper way to do it but you have to pay to play

A current probe would need to be placed inline with the circuit. An amp clamp simply clamps around a wire and does not interfere with the operation of the circuit. An amp probe can change the electrical properties of the circuit you are trying to measure. I know that most engineered things have overhead built into them. It's usually not more than 25% more than the greatest expected load. Something fused at 20a may only draw 6a most of the time. It's fused at 20a because sometimes it may see a spike of 18a. You can't just assume because it has a larger fuse you can go run up against that limit. Why do you need me to keep proving you are overloading the FPCM? They are failing on you!

OK, lets try this again. Stock fuel pump = about 8amps FPCM designed for about 8 amps. If you try to use more than that, the FPCM will die. It's that simple. It doesn't matter if you run 1/0 wire to the FPCM, it will still burn up. I run E85 and my actual HP is close to 450hp at the crank completely uncorrected. There is no reason a pump can't do 100% all the time. The same company that has the Pump Controller I posted earlier should also be releasing a twin pump sending unit that fits our cars in the next few weeks.

it's actually an amp clamp and I see higher current at idle and lower current towards redline. The more fuel the engine uses the easier it is to pump it to it. Stock Fuel pump is around 6-8 amps. Walbro 255 is around 8-10 amps. AEM 320lph should max out around 14a. Aero 340 should max our around 18a Walbro 460 sits around 19a no matter what (apparently). I also noted this in the first line of the Aero install instructions... "The factory fuel pump wiring may not be sufficient to handle the current draw of the Aeromotive 340 Stealth pump. To achieve the advertised flow at pressure, the use of an aftermarket wiring kit such as Aeromotive P/N 16301, including 10-gauge wire and a direct alternator supply point, is required." Continuing to use the FPCM is futile. You guys want modded faster cars, you lose variable pump control. You want variable pump control? Shell out $1000 for a Fuelabs setup. Or you can wait for this to become available of which I will be a primary dealer... hoping for a $300 price point.

I run a stock FPCM and stock wiring with a walbro 255 that is over 6 years old and should be replaced. This currently supports about 450hp.

17amps at 43psi. 18-19 at 60psi.

I usually see around 17amps on an Aeromotive 340 as measured by an amp clamp. I also rarely see Aeromotive 340's live up to their spec sheet. I'm not going to be using them anymore for customers because of my experiences with them over the last 5 years, the final one being last week. I'm pretty sure lots of people have 340's in legacy's as well. They're just not on here. Yes, everything you guys are doing is HELPING. But it's not fixing the problem. The problem is that the FPCM is not designed to run a pump larger than stock and unless you redesign the module, you'll always have a problem.

The modules were designed for a certain amp draw. You are putting in pumps that require more amps. The modules can't keep up. Big surprise. You need to find an aftermarket fuel pump controller (there aren't any at an affordable price) or you need to modify the stock one to handle higher current. Unless an electrical engineer decides to take this on in his free time, you guys are chasing your tails... with BANDAIDS edit: Fuelabs makes some pump / regulator combos that would solve all your issues properly. But you'll have to pay for it.

O, your band aid stopped working? Time to hardwire it.